Self-controlled strand annealer



March 21, 1961 B. c. ELLIS, JR 2,976,397

SELF-CONTROLLED STRAND ANNEALER Filed Jan. 30, 1957 3 Sheets-Sheet 1INVENTOR. B. C. ELL/S, JR.

BY Q.Q..

ATTORNEY March 21, 1961 B. c. ELLIS, JR 2,976,397

SELF-CONTROLLED STRAND ANNEALER Filed Jan. 30, 1957 5 Sheets-Sheet 2INVENTOR. B. C. ELL/$.JR.

ATTORNEY March 21, 1961 B. c. ELLIS, JR 2,976,397 SELF-CONTROLLED STRANDANNEALER Filed Jan. 50, 1957 5 Sheets-Sheet 5 FIG. 4

FIG. 3

INVENTOR.

a. c. ELL/S, JR.

BY QR.

ATTORNEY United States atcnt O 2,976,397 SELF-CONIRGLLED STRAND ANNEALERBenjamin C. 'Ellis, Jr., Baltimore, Md., assignor to Western ElectricCompany, Incorporated, New York, N.Y., a corporation of New York FiledJan. 30, 1957, Ser. No. 637,285 1 Claim. (Cl. 219-455) This inventionrelates to an improvement in apparatus for electrically heating acontinuously moving conductor, and more particularly, to a device forheating a rapidly and continuously moving conductor, by the utilizationof electrical current, to a predetermined and different temperature atvarious points along the path of travel of the conductors tocontinuously anneal the conductor.

This invention is applicable to many operations in connection with manymanufacturing processes but is here illustrated as particularlyapplicable to the electrical heating of a continuously moving conductorwhich is in motion between a supply source and prior to delivery ofbright, annealed, unoxidized conductor at a predetermined temperature toan extruding apparatus for the purpose of raising the temperature of theconductor, which has previously been hardened as a result of coldWorking of the conductor in a drawing operation, a sufiicient amount topartially or completely anneal the conductor, as

may be desired in any venting overheating of prevent discoloration giveninstance, and especially prethe surface of the conductor to thereofwhile it is exposed to the oxidizing influence of the atmosphere andsubsequently drying the conducting, prior to extruding an insulatingsheath thereon, to control adhesive qualities between the insulation andthe conductor, to prevent blisters and bubbles from forming the qualityof the plastic sheath applied thereto.

An object of the present invention is to provide apparatus for heatingcontinuously moving conductor by direct passage of electrical currenttherethrough, in which the conductor passes over at least three sheavesarranged to form paths of unequal lengths to which currents of unequalamounts and the same voltage are applied to the paths between thesheaves so as to cause unequal heating of the conductor along differentpaths of the conductor while maintaining the conductor entering andleaving such apparatus at substantially the same potential, so that thepossibility of electn'cal shock to the operator of the apparatus isminimized and potential differences from the conductor and other outsideapparatus does not occur.

Yet another object of the invention is to provide an apparatus forannealing copper conductor in which the electrical heating current inthe conductor causes uniform annealing to take place regardless of thespeed of movement of the conductor therethrough without the need ofcontrolling the voltage applied in accordance with a variation in speedof the conductor and which is stable even though the copper conductor isnot fully annealed.

Still a further object of the present invention is to provide anopen-ended insulating tube having an auxiliary source of cooling medium,such as steam, for surrounding the moving conductor while it is beingannealed to prevent the outside surface of the conductor from attaininga temperature above which excessive oxidation will occur and so arrangedthat the lengths of the portion of the conductor heated by the currentand the portion cooled'by steam be reduced to a minimum, thereby ininthe'plastic sheath and improve- Patented Mar. 21, 1961 suring that theannealing apparatus will operate at maximum efliciency.

Another object of the invention is to sub ect the conductor to a steamblast to remove the water and foreign matter from the surface thereof,while the conductor 1s being heated so that upon exposure to theatmosphere, any remaining moisture is immediately evaporated to providea dry conductor of a predetermined temperature at the entrance to theassociated extruder.

A further object of the invention is to provide an apparatus forcontinuously annealing, insulating and reeling conductor which will berelatively simple in operation, inexpensive to build, compact,eflicient, and a durable device.

Other objects and features of the invention will be more readilyunderstood from the following detailed description when read inconjunction with the accompanying drawings, in which:

Fig. 1 is a fragmental top plan view of the combined annealingapparatus, source of supply of the conductor, and extruder;

Fig. 2 is a side elevation view of the annealing apparatus, taken online 2-2 of Fig. 1;

Fig. 3 is an end elevation view of the annealing apparatus, taken online 3-3 of Fig. 1;

Fig. 4 is a rear elevation view of the annealing apparatus, taken online 4-4 of Fig. 1;

Fig. 5 is a schematic diagram of the electrical circuitof the annealingapparatus of Fig. '1, and

Fig. 6 is a cross sectional view of a modified form of the annealingtube utilized in the annealing apparatus.

Referring now to the drawings, the strand annealer, designated generallyby the numeral 10, is designed to be used in operations involvingextruding apparatus, designated generally by the numeral 11, demandingcontinuous operation, and may be positioned between a supply, designatedgenerally by the numeral 12, of bare copper conductor '13 and theplastic extruder 11 which will supply a sheath 14 of plastic insulationupon the conductor 13. The conductor 13 that is fed to the extruder 11may be of any desirable cross section or configuration but must beannealed to the desired degree of softness, since, the conductor 11,when it is drawn through the die means (not shown) in the wire drawingoperation, is subjected to a certain amount of working and thereforehardening. As the copper conductor 13 advances continuously through thestrand annealer 10 it is cleaned, straightened, annealed, cooled andthen reheated to a predetermined temperature at which time it enters theplastic extruder l1.

The strand annealer 10 includes a plurality of sheaves to guide theconductor :13 through a predetermined path, at least three of which areelectrically conductive contact sheaves 21, 22 and 23, each of which areinsulated electrically from the remainder of the annealing apparatus 10,and through which electrical current is supplied which causes thetemperature of the conductor 13 to increase progressively from onecontact sheave to the other as the bare copper conductor 13 is advancingcontinuously on its way to the plastic extruder 11. The contact sheaves21, 22 and 23 are preferably spaced to provide a predetermined length ofconductor 13 therebetween, so that the conductor 13 in passingprogressively over the contact sheaves 21, 22 and 23 is dividedelectrically into two sections 24 and 26. The first section 24 is forheating to anneal the conductor 13 and the second section 26 for heatingto dry the conductor 13. The path lengths situated between the contactsheaves 21 and 22 and contact sheaves 22 and 23 are the annealing leg 24and reheat leg 26, respectively. The length of the paths in theannealing leg 24 and the reheat leg 26 are approximately 5 feet and 25feet, respectively.

The conductor 13 which is supplied from a supply reel 27 or 28 into theannealing leg 24, wherein the conductor 13 first passes over a sheave 29which serves to hold "more of the conductor 13 in contact with sheave21, and then over the electrically conducting sheave .21, which servesas one terminal of the electrical circuit for heating the conductor 13in the annealing operation. From the sheave 21, the conductor 13 passesthrough annealing leg 24 and partially around the second electric-allyconducting sheave 22, which may or may not be submerged partially in aquenching bath 31, which serves as a second electrical terminal on theannealing leg 24-, so that the portion 24 of the conductor 13between-the contact sheaves 21 and 22 is a conductive part of theannealing leg 24 and, while it is in contact with the sheaves 21 and 22,the conductor 13 is conducting electricity and is being heated as aresult thereof.

The current for producing the annealing heat in the conductor 13 may beeither alternating or direct but is preferably in the form ofalternating current produced in the secondary of a transformer 33. Theheating of the conductor 13 is accomplished by the utilization of anelectrical circuit in which the contact sheaves 21, 22 and 23 areenergized to pass current through the sections 24 and 26 of theconductor 13 therebetween. The contact sheaves 21, 22 and 23 draw powerfrom a suitable source such as the transformer, designated generally bythe numeral 33. Preferably the two sections 24 and 26 of conductor 13are supplied with electrical current from two parallel circuitsenergized by the secondary 37 of the power transformer 33. In theannealing leg 24, current is supplied to sheave 21 from one side of thesecondary 37 of the transformer 33 and to sheave 22 from the other sideof the secondary 37. In the reheat leg 26, current is supplied to sheave22 from one side of the secondary 37 and to sheave 23 from the otherside of the secondary 37.

It has been thought in the past that the speed at which the conductor 13is passed through the annealing apparatus must bear a certainrelationship to the voltage applied to a certain length of the conductor13 in order to produce a desired amount of annealing in the conductor13. Thus, it has been thought that if the voltage applied to a givenportion of conductor 13 moving at a particular 7 7 speed is onlysuficient to produce'the desired amount of annealing of the conductor13, that a higher speed and the same applied voltage would fail toproduce the same desired amount of annealing, whereas a lower speed withthe same voltage would produce an excessive amount of annealing.However, by utilizing the present invention it is possible to obtain adesired amount of annealing at a wide variation in speeds withoutvarying the applied voltage in a given length of conductor 18.

In operation, the applied voltage is increased to a point where anadditional increase in voltage does not produce a corresponding increasein current flowing in the conductor 13. This occurs because of thetemperature coeificient of resistance of the conductor and the radiationof heat from the conductor. This provides a self-adjusting phenomenawhich with the construction described in the apparatus of the presentinvention will provide annealed copper conductors 13 over a range inspeed from 2000 to 3000 feet per minute with'variation in elongation ofonly 26% to 29%.

The surface of the metal exposed to atmospheric conditions has atendency to tarnish or oxidize which is greatly accelerated when themetal is heated to annealing temperatures. In the case of copper,oxidation is more pronounced than most other metals. While the conductor13 is at an annealing temperature, it is important to protect it fromoxidation by the atmosphere or keep the surface of the conductor 13 at atemperature below the point at which it discolors when in contact withthe atmosphere.

It is thought that even if an inert atmosphere is furnished around theheated conductor 13 to prevent discoloring thereof that the conductor 13may still discolor.

This may be explained by the fact that the free oxygen in the copper,which is in the neighborhood of 0.03%, is driven out by heating thecopper in the conductor 13. The present theory is that if the surface ofthe conductor 13 is prevented from reaching the temperature at which thediscoloration takes place (approximately 270 C.), there is no need toprovide an inert atmosphere to protect the conductor 13 from oxidationas is indicated above.

Using this theory and the fact that with a given set of conditions forany particular strand annealing machine 10, the point along theannealing leg 24 where the conductor 13 reaches the temperature at whichdiscoloration takes place can theoretically be pinpointed since thetemperature of the conductor 13 in the annealing leg 24 will varylogarithmically from one sheave 21 to the other 22. The surface of theconductor 13 in the portion of the annealing leg 24 between that pointand the sheave 22 must be cooled in some manner to prevent thetemperature of the surface from increasing above the temperature atwhich the conductor 13 will discolor as the material in the interiorregions of the conductor 13 is heated to a higher temperature to annealthe conductor 13, which is in excess of 400 C., depending on the timeduring which the conductor 13 is maintained at this temperature.

In the preferred practice of the invention, the portion of the conductor13 in the annealing leg 24 which is heated to a temperature at whichexcessive oxidation will take place is surrounded by an open-endedannealing tube 38 which is positioned vertically with the lower endthereof secured to and projecting a short distance through the top cover41 of a housing 42 which surrounds the contact sheave 22.

The conductor 13 is directed downwardly through the hollow tube 38containing steam supplied from an auxiliary source (not shown). Steamunder pressure is introduced into the annealing tube 38 through a steaminlet connection 43 near the lower end thereof. The steam operates as acleaning medium and a cooling medium to maintain the temperature on thesurface of the conductor 13 at a temperature low enough to preventexcessive oxidation while heat is continuously applied to the conductor13 by the electrical current, to heat the interior of the conductor 13to its annealing temperature. Some of the steam escapes into the housing42 and partially fills the interior thereof and condenses and falls intothe bottom of the housing.

A modified embodiment of the annealing tube 38 is illustrated in Fig. 6and designated generally by the numeral 44. The annealing tube 38 may beshortened and provided with a small metal tube 46, filled with plasticmaterial 47 except for a bore through which the conductor 13 passes, inone end thereof. The plastic material is used to electrically insulatethe conductor 13 from the tube 46. The plastic filled metal tube 46 isutilized as a seal to prevent excessive steam from escaping upwardlyfrom the annealing tube 44, and may be replaced or changed when it isdesirable to anneal a different size of conductor. Ceramic guide bushingseals 49, 50 and 51 are secured in the ends of the tubes 44 and 46, areused to insulate the conductor 13 electrically from the grounded tube 44and serve to prevent wearing of plastic material 47 and tubes 44 and 46.The modified annealing tube 44 may be relatively short since it ispossible to determine the point in the annealing leg 24 at which thetemperature of the conductor 13 will approach a point to which excessiveoxidation would occur and the surface of the conductor 13 need only becooled from that point on as discussed above.

After emerging from the annealing tube 38 the conductor advancespartially around the contact sheave 22 to enter a vertically extendingcooling tube 52 which is situated between contact sheave 22 and an idlersheave 53. Cool water is introduced into the cooling tube 52 at the topend thereof and the flow of the cooling water is controlled so that asubstantially predetermined amount of cooling of the' conductor 13 takesplace therein. The cooling water enters the top of the cooling tube 52,is supplied from an auxiliary source (not shown) at a relatively lowtemperature, emerges at the lower end thereof and spills into the bottomof the housing 42 wherein it collects and flows through an opening inanoverflow drain 54.

It will be understood that the contact sheave 22 may ormay not besubmerged in the body of water 31 contained within the housing 42 sincethe overflow drain 54 has two openings 56 and 57, either of which may beclosed depending on whether it is desired to submerge a contact sheave22 partially in the water 31 to prevent the sheave 22 and the portion ofthe conductor 13 in contact therewith from becoming overheated.Additional heat will not be added to the portion of the conductor 13 incontact with the sheave 22 after the conductor 13 contacts the sheave 22on the approach side and until the conductor 13 leaves the sheave 22 onthe recess side and moves into the reheating leg 26, and, therefore, anycooling that would be necessary while the conductor 13 is in contactwith the sheave 22 is only enough to dissipate the heat being conductedto the surface of the conductor 13 from the material inwardly of thesurface thereof.

Immediately after emerging from the cooling tube 52 any remainingmoisture on the advancing conductor 13 is removed by means of aconventional steam wiper 58 to remove any water or foreign materialwhich remains on the conductor -13. The conductor 13 then makes severalloops about an intermediate sheave assembly, designated generally by thenumeral 59, and then advances partially around electric contact sheave23 to form a path of a variable predetermined length which forms thereheat leg 26. The length of the conductor 13 in the reheat leg 26 maybe varied by changing the relative positions of sheaves 55-55 andsheaves 60-60, in sheave assembly 59 by changing the position of sheaves5555 in the slot 50 or by passing the conductor around a fewer orgreater number of sheaves 55--55 and 60-60. The purpose of the reheatleg 26 is to accomplish the reheating of the conductor 13 to insure thatthe conductor 13 willexit from the anealer after passing through thecooling tube 52 in a dry state and at a predetermined temperature.

After advancing partially around the contact sheave 23, the conductor 13travels around a jockey sheave assembly 61 which in turn is connected toa speed control rheost-at 62 forming a part of the drive system 63 toprovide an accurate speed control for the conductor 13 as it travelsthrough the annealer 10 to control the tension in the conductor 13between the anealer 10 and extruder 11. The conductor 13 is guidedthrough an extruder :11 to eXtrud-e a sheath 14 of an isulated materialthereon and then to apropriate takeup means (not shown).

The temperature of the reheated conductor 13 may be accuratelycontrolled by varying the length of the leg 26 to vary the currenttherein. Since the current in the two legs 24 and 26 will be different,the drop across the sheaves 21 and 23 will be different amounts.Therefore, in order to keep the potential of the portion of theconductors contacting sheaves 21 and 23 equal, a rheostat 64 is providedwhich forms a part of the circuit for energizing the contact sheave 23.Whenthe length of the conductor 13 in the reheat leg 26 is varied tovary the current therein, the value of the resistance in the rheostat 64must also 'be varied to make the drop across the rheostat 64 and thesheave 23 equal to the drop across the sheave 21 to insure that theportions of the conductor 13 entering and recessing from the annealer 10are both at the same potential to prevent externally grounded paths andpossible arcing of the conductor to ground.

It will be understood that the cooling tube 52 and the reheat leg 26 areboth situated between the electrical contact sheaves 22 and 23 andaccordingly the conductor 13 is being heated as it passes through thecooling tube 52.

6 However, the cooling afiect of thewater flowing through the coolingtube 52 is by design suflicient so that the conductor 13 is cooledsubstantially to the temperature of the water before being reheatedduring the remainder of the travel through the reheat leg 26 from thecooling tube 52 to the contact sheave 23.

The apparatus of the present invention heats the condoctor 13 as ittravels at a comparatively high rate of speed and the temperaturerequired to anneal or soften the metal is generally so high that thetensile strength thereof is greatly reduced. Therefore it is preferableto prevent the conductor 13 from being stressed beyond its elastic limitby propelling the conductor 13 positively at both sides of the heatingzones 24 and 26 to avoid stretching the soft portion of the conductor 13therein.

by reducing the tension in the heated sections 24 and 26 of conductor 13to a minimum. This may be accomplished by having all contact sheaves 21,22 and 23 of the same diameter and driven at the same speed from thesame source 63, through belt means 65, 66 and 67, the speed of which maybe controlled by the jockey sheave 61.

It is to be understood that the above-described arrangements are simplyillustrative of the invention. Numerous other arrangements may bereadily devised by'those skilled in the art which will embody theprinciples of the invention and fall within the spirit and scopethereof.

What is claimed is:

Annealing apparatus in which a moving conductor is heated by the passageof electrical current therethrough, which comprises at least threesheaves to guide the conductor in a predetermined path, at least threeof said sheaves being electrically conductive contact sheavesindividually insulated from the remainder of the annealing apparatusover which the conductor to be annealed is progressively passed at avariable speed, means for supplying electrical energy at a substantiallyconstant voltage connected to the conductor through two of said sheavesto progressively heat successive portions of the conductor of apredetermined length to anneal the same, an annealing tube which is sopositioned between said last two mentioned sheaves that the successiveportions of the conductor passing at variable speeds therebetween aredirected to said tube and which includes an elongated tube, a secondelongated tube of comparatively small cross-sectional dimensions securedin one end of said rst-mentioned elongated tube for sealing the endthereof, a plastic composition lining the interior of said secondelongated tube except for a bore of substantially the samecross-sectional dimensions as the conductor passing therethrough, and aplurality of ceramic guide bushings secured within said tubes forguiding the conductor and electrically insulating the conductor fromsaid tubes, means to supply steam to said annealing tube for cooling andcleaning the surface of the conductor and preventing oxidation thereof,the means for supplying the electrical energy being connected to theannealed conductor through a third sheave and the last one of said lasttwo mentioned sheaves over which successive portions of the conductorpass at variable speeds to progressively heat a section of saidconductor of a predetermined length to a predetermined temperature, acooling tube which is so positioned between said third sheave and saidlast one of the last two mentioned sheaves that the successive portionsof the conductor passing therebetween are directed through said coolingtube, means to supply cooling fluid to said cooling tube, steam wipermeans positioned adjacent to said cooling tube for wiping the conductorwhereby the portions of the conductor leaving the cooling tube arecleared of moisture and foreign material, variable speed means forrotating said electrically conductive sheaves at equal peripheral speedsfor propelling the conductor progressively at both sides of each of theheated sections of the conductor for preventing stretching of theconductor, and variable resistance means to com- References Cited in thefile of this patent UNITED STATES PATENTS Procunier Apr. 25, SheperdsonJuly 27, Alexander et al. May 3, Cook Jan. 4, Hanson et a1. Mar. 22,OGrady Mar. 18, Rendel Nov. 10, OGrady Dec. 13,

